## CAMB, unable to perform complicated calculations

Use of Healpix, camb, CLASS, cosmomc, compilers, etc.
Posts: 7
Joined: August 19 2018
Affiliation: IAUCTB

### CAMB, unable to perform complicated calculations

I have written equations of a holographic dark energy model with interaction in CAMB. (w_de rho_de which are ODE and must be solved numerically).
I have tested the CAMB with simple code and it printed list of numbers so fast and plotted it using Gnuplot.
But, as I replace the equations with my model, CAMB takes more than 10 hours to print just half of that list while saying rombint failed to converge...
I do not know how should I do, the equation I wrote for my model is ODE which works properly. I use RungeKutta 45 for solving that (w_de)

this is my w_de
w_de =-1-(1/(3 * rkomgd(a))) * (3 * wa_ppf * (rkomgd(a) + rkomgd(a)**2/((3 * rkomgd(a)/w_lam**2) - 2)) + 3 + rkomgd(a) * (2 - 3/(w_lam**2))) * (-3 * (-2 + rkomgd(a) * ((3/w_lam**2) - 1)) + 3 * wa_ppf * (rkomgd(a) + rkomgd(a)**2/((3 * rkomgd(a)/w_lam**2) - 2)))/(rkomgd(a) * ((3/w_lam**2) - 1) - w_lam**2 - 1)
in which rkomgd(a) is solving another fuction using runge kutta

also my qrho_de is rkomgd(a)

Antony Lewis
Posts: 1534
Joined: September 23 2004
Affiliation: University of Sussex
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### Re: CAMB, unable to perform complicated calculations

For the background evolution you should precompute and interpolate the functions, like what use_tabulated_w option does for equations_ppf or the improved devel branch.

Posts: 7
Joined: August 19 2018
Affiliation: IAUCTB

### Re: CAMB, unable to perform complicated calculations

Antony Lewis wrote:
August 24 2018
For the background evolution you should precompute and interpolate the functions, like what use_tabulated_w option does for equations_ppf or the improved devel branch.
Thank you. my rho_de is ODE. If I use w_de from table, solving rho_de gets error again?

Posts: 7
Joined: August 19 2018
Affiliation: IAUCTB

### Re: CAMB, unable to perform complicated calculations

August 24 2018
Antony Lewis wrote:
August 24 2018
For the background evolution you should precompute and interpolate the functions, like what use_tabulated_w option does for equations_ppf or the improved devel branch.
Thank you. my rho_de is ODE. If I use w_de from table, solving rho_de gets error again?
Nope, it works properly using table and rungekutta simultaneously.

srijita sinha
Posts: 11
Joined: April 12 2019
Affiliation: Indian Institute of Science Education and Research Kolkata

### Re: CAMB, unable to perform complicated calculations

Hi,

I am also trying to solve for holographic model. I solved the background evolution equations seperately and then interpolated those using spline and cubicsplint. In a seperate code every thing works fine. When put into equation_ppf.f90 the background evolution part itself is working well. But
rombint2 failed to converge
warning message is there. After 10mins the code stops with message

Code: Select all

Reionization_zreFromOptDepth: Did not converge to optical depth
tau = -3.053052958849836E-005 optical_depth =   9.000000000000000E-002
50.0000000000000        49.9984741210938
(If running a chain, have you put a constraint on tau?)
Error result Reionization did not converge to optical depth

Thanks
Srijita

Antony Lewis
Posts: 1534
Joined: September 23 2004
Affiliation: University of Sussex
Contact:

### Re: CAMB, unable to perform complicated calculations

Looks like an optical depth issue. However equations_ppf.f90 does not exist in version 1.x so you must be using an old version.

srijita sinha
Posts: 11
Joined: April 12 2019
Affiliation: Indian Institute of Science Education and Research Kolkata

### Re: CAMB, unable to perform complicated calculations

I am using CAMB-0-1-7. Which one should I use?

Antony Lewis
Posts: 1534
Joined: September 23 2004
Affiliation: University of Sussex
Contact: